If you mean the Ordo Hereticus Strike Force in CJ49, I hear it can be pretty devastating if it all comes in on the 2nd or 3rd turn. The problem with it is the problem with any deepstrike/reserves army, if it comes in piecemeal, it gets chewed up.
However, it is an extremely cool concept, I just think the current reserve rolls poorly simulate what should be a coordinated assault.
AX